The Man from Planet X (1951)

To study a rogue planet heading for a near-miss with Earth, Prof. Elliot sets up an observatory on the foggy moors of a remote Scottish island, with his pretty daughter and Dr. Mears, a former student with a shady past. Soon after arrival of reporter John Lawrence, a ship from Planet X just happens to land near the observatory. Is the visitor (who actually looks alien) benevolent? What are Mears' real motives for trying to communicate with it?